Question

Why chlorine has more electron affinity as compared to fluorine?

Answer 1

The electron gain enthalpy of chlorine is more negative than fluorine. This is because fluorine is smaller in size than chlorine. Thus the extent of electron-electron repulsion would be more in fluorine than in chlorine. Because of this, the incoming electron would face more repulsion in fluorine than in chlorine. Chlorine on the other hand being larger in size, accepts the electron more readily than fluorine.

In other words, the chloride ion is formed more easily than the fluoride ion.